Revert "Removed HOUDINI_BIN variable in favor of multiple search paths." (#214)
Revert "Removed HOUDINI_BIN variable in favor of multiple search paths." (#214)

This reverts commit 453443b483fa7a1f99fc9f2f8f181f174591b5f7.
tangent-opensource/hdBlackbird,tangent-opensource/hdBlackbird,tangent-opensource/hdBlackbird